The desiccant tablet is one of the products in a wide range of products that absorb moisture from the air. The main characteristic of this type of tablet's operation is that it absorbs moisture in layers, i.e. real-time operation, since, in conditions where relative humidity is higher that 55-60%, the first layer of the product is used up, thus releasing a brine into its bottom container; and, conversely, if humidity is lower than 55-60%, the desiccant tablet will not operate, and ceases to release brine, so the presence or absence at moisture in the air can be detected thereby in real time.
Said desiccant tablet is based on calcium chloride, a hygroscopic and deliquescent salt with the ability to absorb ambient moisture. To these aromatic substances may also be added to combine a desiccant function with an air-freshening function as described in patent ES2353556. However, these desiccant active compounds are labeled with the pictogram Xi (irritant) and risk phrase R36 (irritating to eyes), as well as the safety phrases S22 (do not breathe dust) and S24 (avoid contact with skin). In order to avoid contact with the skin, various packaging and encapsulation systems have been used. Among these, one of the most novel is the use of a special type of non-woven textile material, hereinafter referred to as non-woven. This type of cloth is used due to the fact that it is an engineered product whose properties can be artificially designed. Specifically, it can be a material with a very long life or a short one; its functions can include absorption, liquid repellence, resilience, elasticity, plasticity, or durability; such cloths can also be fire-proof, washable, can be used as a stuffing material, as a bacterial barrier for filtering compounds, or for their sterility.
U.S. Pat. No. 2,649,923 describes a bag made from non-woven that hangs in order to facilitate the ventilation of a moisture-absorbing compound, which has the disadvantage of operating more slowly, given that it is normally used in small spaces such as closets, shoe racks, etc., where ventilation is low.
Patent EP0686422 has the same disadvantages as mentioned above. A bag that contains two layers of a material that should be permeable to moisture-laden air is disclosed, while at the same time impermeable to the aqueous solution that is generated inside the bag, wherein the active substance with a desiccant reaction is preferably calcium chlorate. The brine that results from the reaction is kept inside the bag itself by means of an absorbent material.
Patent US2008/0206459 protects an invention relating to a non-woven moisture-absorbing material that can be recycled after it has been used. However, it is a complex fabric, made up of three different layers, which are meant for applications in which it is not necessary to absorb a large amount of moisture since the maximum index is 65% of its weight after 5 hours exposed to conditions of high relative humidity, thus reducing its absorption capacity to 18-36% by weight once the damp material has been recycled under drying conditions of 120° C.
Patent FR2750618 addresses some of the problems mentioned above because it is a device comprising two chambers, wherein the upper portion contains the water-absorbing hygroscopic active compound, which pours the brine into the lower chamber. This solution, which is adequate for addressing the problem of reducing air moisture, is not optimal because there is a layer of air between the top portion of the hygroscopic material and the non-woven fabric that encapsulates it. This material is made of polyolefin or a cellulosic fabric, but it does not fit snugly against the active substance, giving rise to an inner layer of air with low relative humidity that makes it harder for the hygroscopic active substance to begin operating, and once it is in operational mode, this layer of dry air generates resistance to the transmission of moisture from the external air into the non-woven fabric. The same disadvantages arising from a chamber of dry air between the encapsulation and the tablet are found in patent US2010/0025629, which describes a desiccant tablet encapsulated in a material that is permeable to water vapor, preferably embodied in polyethylene, polytetrafluoroethylene, polyvinylpyrrolidone, or cellulose ether. In addition, this patent describes desiccant tablets that absorb up to 40% of their weight in water, which quantity is far lower than that which will be described in the object of the present invention.